Display device

ABSTRACT

The present invention realizes a display device with dummy pixel portions and a frame region required for the dummy pixel portions and code notation, in which the frame region is minimized while achieving code notation in required size. 
     In a dummy pixel portion ( 122 ) of the present display device, the number of gate electrodes in a thin film transistor formed by a semiconductor layer ( 11 ) is reduced to two, so that distances from a contact hole ( 12 ) to another contact hole ( 13 ) and to a through-hole ( 14 ) can be shortened as compared to those in pixel formation portions ( 112   a,    112   b ), making it possible to dispose the contact hole ( 13 ) and the through-hole ( 14 ) in a lower portion in the figure. In addition, provided in the vicinity of the center of the dummy pixel portion ( 122 ) is only an electrode equivalent to a storage capacitance line ( 170 ). Thus, a wide transparent region can be ensured to note a code ( 22 ) of a sufficient size in the dummy pixel portion ( 122 ).

PRIORITY STATEMENT

This application is a divisional application of U.S. application Ser.No. 11/921,931, filed Dec. 11, 2007 now U.S. Pat. No. 7,812,914, whichis a national phase application of International Patent Application No.PCT/JP2006/311591, filed Jun. 9, 2006, which claims priority to JPApplication No. 2005-278013 filed Sep. 26, 2005, the entire contents ofU.S. application Ser. No. 11/921,931, International Patent ApplicationNo. PCT/JP2006/311591, and JP Application No. 2005-278013 areincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to display devices, and more specificallyto a display device in which liquid crystal elements or EL (electroluminescence) elements are disposed in the form of a matrix.

BACKGROUND ART

In recent years, flat-panel display devices as typified by liquidcrystal display devices have been in practical use, and mounted in avariety of types of electronic equipment, in particular mobileelectronic equipment. Widely-used flat-panel liquid crystal displaydevices are thin liquid crystal display devices of active matrix typecapable of high-resolution display.

FIG. 11 is a view schematically illustrating the structure of such aconventional active matrix liquid crystal display device. The activematrix liquid crystal display device is composed of two boards having aliquid crystal layer sandwiched therebetween, in which an element board100, one of the two boards, has disposed thereon in the form of alattice a plurality of unillustrated source bus lines and a plurality ofunillustrated gate bus lines, which respectively act as video signallines and scanning signal lines, and the board also has a plurality ofpixel formation portions disposed in the form of a matrix, at theirrespective intersections between the source bus lines and the gate buslines. The pixel formation portions constitute a display portion of thedevice, and each pixel formation portion includes a TFT (thin filmtransistor) and pixel electrodes, the TFT being a switching elementhaving a gate terminal connected to the gate bus line, and a sourceterminal connected to the source bus line, the pixel electrodes beingconnected to a drain terminal of the TFT. The element board 100including the pixel formation portions is also referred to as a “TFTboard”. In addition, a counter board 200, the other of the two boardsthat is opposed to the element board 100, has a common electrode and acolor filter (CF) provided thereon, the common electrode being anunillustrated counter electrode commonly provided for the pixelformation portions, the color filter being intended to form displaycolors. This board is also referred to as a “CF board”.

Such an active matrix liquid crystal display device includes: a sourcedriver (column control circuit) 130 for driving the source bus lines ofthe display portion; a gate driver (row control circuit) 140 for drivingthe gate bus lines of the display portion; an unillustrated commonelectrode drive circuit for driving the common electrode; and anunillustrated display control circuit for controlling the source driver,the gate driver, and the common electrode drive circuit. In recentyears, it is often the case that, of the above elements, at least thesource driver 130 and the gate driver (column control circuit) 140 areeach composed of polysilicon thin film transistors, and disposed in aframe region 120 on the element board 100, which is provided around adisplay region 110 in which the pixel formation portions are disposed.The configurations of the display region 110 and the frame region 120will be described next with reference to FIGS. 12 and 13.

FIG. 12 is an enlarged top view illustrating a detailed configuration ofa portion of the element board 100 that is included in the areaencircled by circle A shown in FIG. 11. FIG. 12 shows two pixelformation portions 111 a and 111 b, which are provided in the displayregion 110 and have the same configuration, a dummy pixel portion 901,which is provided in the frame region 120 and has the same configurationas those of the pixel formation portions 111 a and 111 b, and a codenotation portion 902 in which a code 21 and predetermined wiring areprovided.

As shown in FIG. 12, the display region 110 has a plurality of gate buslines 150, which are disposed along display rows at predeterminedintervals in the vertical direction of the figure, and a plurality ofsource bus lines 160, which are disposed along display columns atpredetermined intervals in the horizontal direction of the figure.

The gate bus line 150 is connected to gate terminals of thin filmtransistors, which are respectively included in the pixel formationportions 111 a and 111 b and the dummy pixel portion 901, while thesource bus line 160 is connected to a source terminal of a correspondingone of the thin film transistors via a contact hole 12.

Note that the thin film transistor is formed by a semiconductor layer11, and in this case, a gate electrode of the thin film transistorformed by the semiconductor layer 11 is divided into three portions asshown in FIG. 12. By dividing the gate electrode into a plurality ofportions in such a manner, it becomes possible to reduce OFF-current inthe transistor, and thereby to improve the ability to hold a writtenpotential at a predetermined value.

In addition, a drain terminal of the thin film transistor extends out ofa contact hole 13 toward a display surface of the element board 100 (asurface facing the counter board 200) before being connected via athrough-hole 14 to a transparent electrode 16 and a reflective electrode17, which serve as pixel electrodes. Such a layered structure will bedescribed later.

Note that this display device is a so-called semi-transmissive displaydevice, in which a display (hereinafter, referred to as a “transmissivedisplay”) using transmissive light from an unillustrated backlightillumination device, which is positioned opposite to the counter board200 with respect to the element board 100, is effected simultaneouslywith a display (hereinafter, referred to as a “reflective display”)using outside light incident from the outside of the device through thecounter board 200. The semi-transmissive display device is capable ofproviding a readily-viewable display by effecting the transmissivedisplay mainly in a dark place, whereas effecting the reflective displaymainly in a bright place. Accordingly, the pixel electrodes as describedinclude both the transparent electrodes 16 for the transmissive displayand the reflective electrodes 17 for the reflective display, but thedisplay device may include only pixel electrodes of either type.

A storage capacitance portion 15, which is also referred to as an“auxiliary capacitance”, is additionally provided to hold the potentialsof the pixel electrodes. One of two electrodes included in the storagecapacitance portion 15 (which is provided at the side opposite to thecounter board 200) linearly extends as a storage capacitance line 170out of the display region 110 and passes through the frame region 120 inthe row direction.

A repair portion 18, which is composed of a pair of electrodes having apredetermined insulating layer sandwiched therebetween, is provided torepair any defect of the pixel formation portion that has occurredduring manufacture. For example, if a predetermined potential from thesource bus line 160 cannot be written onto the pixel electrode for sucha reason that the thin film transistor in the pixel formation portionhas been disconnected during manufacture, such a defective pixelformation portion is undesirable because it appears as a bright spot (inthe case of a normally-white-type display device). Therefore, the pairof electrodes included in the repair portion 18 are fused together byirradiating them with laser or suchlike, making it possible toelectrically connect the pixel electrode to the source bus line. As aresult, the defective pixel formation portion that appears as a brightspot is turned into a black spot, making it possible to make the displaydefect less noticeable.

The dummy pixel portion 901 is identical in configuration and size tothe pixel formation portions 111 a and 111 b, but it does not form apixel (i.e., it is not used for effecting a display). In general, suchdummy pixel portions are disposed in a position corresponding to adisplay row or column adjacent to the periphery of the display region110. The dummy pixel portions prevent: (1) breakage of the pixelformation portions due to static charge; (2) lighting with unevenbrightness due to different parasitic capacitances in the pixelformation portions provided in the vicinity of the periphery of thedisplay region 110; and (3) an abrupt change of the cell gap (height)between the vicinity of the periphery of the display region 110 and theframe region 120. Note that, in some cases, to further enhance suchadvantages of the dummy pixel portions, two or more dummy pixel portionsare disposed together in the vicinity of one end of a single display row(or display column).

Since the structure of the semiconductor layer 11 for forming the thinfilm transistors is well-known, any detailed description thereof will beomitted herein, but layered structures of the element board 100including the semiconductor layer 11 will be briefly described withreference to FIGS. 13A through 13D.

FIGS. 13A through 13D are schematic views illustrating the pixelformation portions 111 a and 111 b, the dummy pixel portion 901, and thecode notation portion 902 in cross section taken along line A-A shown inFIG. 12. More specifically, FIG. 13A is a view illustrating an examplewhere the code 21 in the code notation portion 902 is formed by areflective electrode, FIG. 13B is a view illustrating an example wherethe code 21 is formed by a source electrode, FIG. 13C is a viewillustrating an example where the code 21 is formed by a gate electrode,and FIG. 13D is a view illustrating an example where the code 21 isformed by a semiconductor layer.

As shown in FIG. 12, the code 21 is the number “111” provided in theframe region 120, indicating a display row or column number within thedisplay region 110. This number is used for process management andanalysis of the element board 100 or a liquid crystal cell.

Note that the code 21 is disposed so as to be viewable from the displaysurface side of the element board 100 (as shown in FIG. 12), or the code21 may be disposed with the number being inverted, so that it isviewable through a glass substrate of the element board 100 from theside opposite to the display surface.

As shown in FIG. 13A, the code 21 can be made up of the same reflectiveelectrode material as that for the reflective electrode 17 to increasevisibility. However, light traveling toward the frame region 120 aroundthe display region 110 might be blocked by a predetermined black matrixformed on the counter board 200, and therefore the same electrodematerial as that for the gate electrode, or the source electrode, whichis a thin film made up of metal and having a light-blocking effect, isoften used in order to ensure the visibility of the code 21, as well asto form the code 21 in an early stage.

Specifically, an unillustrated silicon thin film is first formed on aglass substrate 51 of the element board 100, and furthermore, after agate insulating film 52 is formed thereon, gate electrodes and aninterlayer insulating film 53 are formed. Thereafter, drain electrodesand source electrodes of thin film transistors are formed in contactholes that have been made to expose the silicon thin film. After aflattened layer 54 including a passivation film is further formedthereon, through-holes 14 and other holes are made. The transparentelectrodes 16 made up of ITO (indium tin oxide) are formed above theholes, and the reflective electrodes 17 are then formed using aconductive material such as aluminum or silver. In the case of formingthe code 21 using the reflective electrode, the formation is carried outin a rather late stage, and therefore the code 21 is often formedsimultaneously with the source electrode as shown in FIG. 13B, or thegate electrode as shown in FIG. 13C, using the same material as that forthe electrode. Furthermore, the code 21 may be formed simultaneouslywith the semiconductor layer 11, which is the aforementioned siliconthin film, as shown in FIG. 13D, using the same material as that for thesemiconductor layer 11. Note that the silicon may be amorphous silicon.

Here, the code 21 can be made up of a thin-film material (e.g., a colorfilter) on the counter board 200, rather than on the element board 100.However, if the code is formed on the counter board 200 withoutconsidering the positions of various conductors and circuits that are tobe formed on the element board 100, such conductors and circuits havinga light blocking effect make it difficult to read the code on thecounter board 200 through the glass substrate from the side opposite tothe display surface of the element board 100. Also, in such a case, partor all of the code is often rendered impossible or hard to view evenfrom the counter board 200 side. Therefore, it is preferable that thecode 21 is disposed on the element board 100.

[Patent Document 1] Japanese Laid-Open Patent Publication No.2004-163600

[Patent Document 2] Japanese Laid-Open Patent Publication No.2000-292805

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In order to ensure code readability, however, the code 21 is in generalrequired to be about 0.01 to 0.1 mm in size, and in the case where thedummy pixel portion 901 and the code notation portion 902 including thecode 21 are disposed in the frame region 120 on the element board 100 asshown in FIG. 12, the area of the frame region 120 is increased. Inaddition, even if the code 21 is formed on the counter board 200, inorder to make the code 21 more viewable, an unused region equal in sizeto the code notation portion 902, where no conductors and circuits aredisposed, is required in a portion of the frame region 120 that isvertically distanced from the portion where the code 21 is disposed.Therefore, even in this case, the area of the frame region 120 isincreased as well.

The increase in size of the frame region 120 that is not involved ineffecting displays only results in a larger overall display size, sothat products having the display device mounted therein are renderedless attractive, and the number of display devices that can bemanufactured from so-called mother glass from which to obtain aplurality of glass substrates as described above is decreased, leadingto an increase in the manufacture cost.

In addition, in the case of forming the source driver 130 and the gatedriver 140 in the frame region 120, as well as any circuit or componentfor implementing an additional function in the frame region 120, theframe region 120 is further increased in size. Specifically, it ispreferable that the frame region 120 is as small as possible asdescribed above, and therefore no wiring region is normally provided inthe frame region 120 in order to lead around (or bend) the gate buslines 150 and the source bus lines 160. Accordingly, the source driver130 and the gate driver 140 that are to be formed in the frame region120 are disposed in limited positions. For example, the gate driver 140is limitedly disposed in a position almost in contact with the codenotation portion 902 shown in FIG. 12. Consequently, it is not possibleto conveniently change positions in which to dispose the source driver130 and the gate driver 140, and thereby to make an extra region inwhich to form any circuit or component for implementing an additionalfunction, without increasing the size of the frame region 120.

Therefore, an objective of the present invention is to provide a displaydevice with dummy pixel portions and a frame region required for thedummy pixel portions and code notation, in which the frame region isminimized while achieving code notation in required size.

Solution to the Problems

A first aspect of the present invention is directed to a display devicecomprising an element board and a counter board, the element boardincluding: a plurality of data signal lines for transmitting a pluralityof data signals; a plurality of pixel formation portions disposed in amatrix form, the pixel formation portions being provided in a vicinityof their respective intersections between the plurality of data signallines and a plurality of scanning signal lines crossing the data signallines; and a plurality of dummy pixel portions, each being disposedadjacent to an outermost one of the pixel formation portions, thecounter board being provided so as to be opposed to the element board,such that electro-optical elements for effecting a display aresandwiched between the counter board and the element board,

wherein the dummy pixel portions each include at least one componentequivalent to any one of a plurality of light blocking effect componentsfor forming a predetermined circuit included in the pixel formationportions, and an area of the component included in the dummy pixelportion, when viewed from a position substantially vertically away froma principal surface of the element board, is smaller than that of eachof the components included in the pixel formation portions.

In a second aspect of the present invention, based on the first aspectof the invention, the pixel formation portions each include any one ormore of the following: a repair portion by which to change wiring in thecircuit; a predetermined memory circuit; and a predetermined sensorcircuit, and the dummy pixel portions include none of the following: therepair portion, the memory circuit, and the sensor circuit, as includedin the pixel formation portions.

In a third aspect of the present invention, based on the first aspect ofthe invention, one of the components included in the pixel formationportions is a semiconductor layer for forming a predetermined first thinfilm transistor, and the component included in the dummy pixel portionsis another semiconductor layer having a smaller area than that of thesemiconductor layer, and the dummy pixel portions each include a secondthin film transistor formed by the smaller semiconductor layer.

In a fourth aspect of the present invention, based on the third aspectof the invention, the first thin film transistor includes a plurality ofgate electrodes, and the second thin film transistor includes a lessernumber of gate electrodes than the number of gate electrodes in thefirst thin film transistor.

In a fifth aspect of the present invention, based on the first aspect ofthe invention, the pixel formation portions each include a storagecapacitance portion having two electrodes for holding a potential inaccordance with a signal supplied from a corresponding one of the datasignal lines, and the dummy pixel portions each include only anelectrode equivalent to one of the two electrodes included in thestorage capacitance portion, the electrode being connected to one of thetwo electrodes included in a pixel formation portion adjacent to thedummy pixel portion.

In a sixth aspect of the present invention, based on the fifth aspect ofthe invention, the electrode included in the dummy pixel portions has asmaller width than that of the one of the two electrodes included in thepixel formation portion.

In a seventh aspect of the present invention, based on the first aspectof the invention, the dummy pixel portions each include a code notationportion in which to note a predetermined code, and the componentincluded in the dummy pixel portions is disposed so as not to preventnotation of the code.

In an eighth aspect of the present invention, based on the seventhaspect of the invention, the components included in the pixel formationportions are a semiconductor layer, a gate electrode, and a sourceelectrode that form a predetermined thin film transistor, and thenotation of the code by the code notation portion is achieved by formingone of the following into a predetermined shape: another semiconductorlayer simultaneously formed with the semiconductor layer; an electrodesimultaneously formed with the gate electrode; and an electrodesimultaneously formed with the source electrode.

In a ninth aspect of the present invention, based on the seventh aspectof the invention, one of the components included in the pixel formationportions is a reflective electrode for effecting a reflective display,and the notation of the code by the code notation portion is achieved byforming an electrode of a predetermined shape, simultaneously with thereflective electrode.

In a tenth aspect of the present invention, based on the first aspect ofthe invention, the counter board includes code notation portions inwhich to note a predetermined code within a region overlapping the dummypixel portions when viewed from a position substantially vertically awayfrom a principal surface of the counter board, and the componentincluded in the dummy pixel portions is disposed so as not to preventnotation of the code.

In an eleventh aspect of the present invention, based on the firstaspect of the invention, the dummy pixel portions are connected toeither the data signal lines or the scanning signal lines, or both, andinclude a pad portion by which to externally input/output apredetermined signal to/from the device.

In a twelfth aspect of the present invention, based on the first aspectof the invention, the display device further comprises a data signalline drive circuit for supplying the plurality of data signals to theirrespective data signal lines, and the data signal line drive circuit isconnected to conductors which are connected to their respective datasignal lines, and extend out of an end of their respective dummy pixelportions after being bent at a predetermined angle in a direction inwhich the data signal lines extend.

In a thirteenth aspect of the present invention, based on the firstaspect of the invention, the display device further comprises a scanningsignal line drive circuit for supplying a predetermined selection signalto the scanning signal lines, and the scanning signal line drive circuitis connected to conductors, which are connected to their respectivescanning signal lines, and extend out of an end of their respectivedummy pixel portions after being bent at a predetermined angle in adirection in which the scanning signal lines extend.

EFFECT OF THE INVENTION

According to the first aspect of the invention, the area of thecomponent included in the dummy pixel portions is smaller than that ofeach of the components included in the pixel formation portions, andtherefore, for example, it is possible to note a code of a required sizein the dummy pixel portions. Thus, it is possible to provide a displaydevice with a reduced frame region required for the dummy pixel portionsand code notation.

According to the second aspect of the invention, the repair portion, thememory circuit, or the sensor circuit, which is included in the pixelformation portions as their component, is not included in the dummypixel portions, and therefore it is possible to reduce the area of thecomponent included in the dummy pixel portions.

According to the third aspect of the invention, the semiconductor layerin the dummy pixel portions is smaller in area than that in the pixelformation portions, and therefore it is possible to further reduce thearea of the component included in the dummy pixel portions, making itpossible to conveniently change the position of the contact hole coupledto the semiconductor layer, for example.

According to the fourth aspect of the invention, the second thin filmtransistor included in the dummy pixel portions has a lesser number ofgate electrodes than the number of gate electrodes in the first thinfilm transistor included in the pixel formation portions, and thereforeit is possible to further reduce the area of the component included inthe dummy pixel portions.

According to the fifth aspect of the invention, the dummy pixel portionseach include only an electrode connected to one of the two electrodesincluded in the storage capacitance portion of the pixel formationportion adjacent thereto, so that there is no region where light isblocked by the other electrode, making it possible to further reduce thearea of the light blocking effect component included in the dummy pixelportion.

According to the sixth aspect of the invention, the dummy pixel portionseach include an electrode (e.g., a storage capacitance line electrode)having a smaller width than that of one of the electrodes included inthe pixel formation portions, and therefore a region where light isblocked by that electrode is reduced in size, making it possible tofurther reduce the area of the light blocking effect component includedin the dummy pixel portion.

According to the seventh aspect of the invention, the light blockingeffect component included in the dummy pixel portions is disposed so asnot to prevent code notation, and therefore it is possible to note aviewable code of a required size in the dummy pixel portions.

According to the eighth aspect of the invention, the code notationportions are formed simultaneously with the semiconductor layer, thegate electrode, or the source electrode, and therefore it is possible tonote a viewable code of a required size in the dummy pixel portions,without increasing the manufacture cost.

According to the ninth aspect of the invention, the code notationportions are formed simultaneously with the reflective electrode, andtherefore it is possible to note a viewable code of a required size inthe dummy pixel portions, without increasing the manufacture cost.

According to the tenth aspect of the invention, the code notationportions are included in a region on the counter board that overlaps thedummy pixel portions, and the component included in the dummy pixelportions is disposed so as not to prevent code notation, making itpossible to note viewable codes of a required size in the regionoverlapping the dummy pixel portions.

According to the eleventh aspect of the invention, the pad portion isincluded in the dummy pixel portions, and therefore it is possible toprovide a display device with a reduced frame region required forproviding the dummy pixel portions and the pad portions.

According to the twelfth aspect of the invention, the data signal linedrive circuit is connected to the conductors that extend out of an endof their respective dummy pixel portions after being bent at apredetermined angle, resulting in an increased degree of freedom inlayout of the data signal line drive circuit in the frame region. Thus,it is possible to add a new function without increasing the size of thedisplay device.

According to the thirteenth aspect of the invention, the scanning signalline drive circuit is connected to the conductors that extend out of anend of their respective dummy pixel portions after being bent at apredetermined angle, resulting in an increased degree of freedom inlayout of the scanning signal line drive circuit in the frame region.Thus, it is possible to add a new function without increasing the sizeof the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the configuration of a liquidcrystal display device according to an embodiment of the presentinvention, along with an equivalent circuit of a display portionthereof.

FIG. 2 is an enlarged top view illustrating a detailed configuration ofan element board in the vicinity of the boundary between a displayregion and a frame region in the embodiment.

FIG. 3 is a view illustrating an example where a source driver and agate driver in the embodiment are suitably positioned.

FIG. 4 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a first variant of the embodiment.

FIG. 5 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a second variant of the embodiment.

FIG. 6 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a third variant of the embodiment.

FIG. 7 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a fourth variant of the embodiment.

FIG. 8 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a fifth variant of the embodiment.

FIG. 9 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a sixth variant of the embodiment.

FIG. 10 is an enlarged top view illustrating a detailed configuration ofthe element board in the vicinity of the boundary between the displayregion and the frame region in a seventh variant of the embodiment.

FIG. 11 is a view schematically illustrating the structure of aconventional active matrix liquid crystal display device.

FIG. 12 is an enlarged top view illustrating the configuration of aportion of an element board of the conventional liquid crystal displaydevice.

FIG. 13A is a schematic cross-sectional view illustrating pixelformation portions, a dummy pixel portion, and a code notation portionin a conventional example where a code is noted by a reflectiveelectrode.

FIG. 13B is a schematic cross-sectional view illustrating the pixelformation portions, the dummy pixel portion, and the code notationportion in a conventional example where the code is noted by a sourceelectrode.

FIG. 13C is a schematic cross-sectional view illustrating the pixelformation portions, the dummy pixel portion, and the code notationportion in a conventional example where the code is noted by a gateelectrode.

FIG. 13D is a schematic cross-sectional view illustrating the pixelformation portions, the dummy pixel portion, and the code notationportion in a conventional example where the code is noted by asemiconductor layer.

DESCRIPTION OF THE REFERENCE CHARACTERS

11 semiconductor layer

12,13 contact hole

14 through-hole

15 storage capacitance portion

16,76,86,96 transparent electrode

17,37,47,87,97 reflective electrode

18 repair portion

21 to 23, 26 to 29 code

51 glass substrate

52 gate insulating film

53 interlayer insulating film

54 flattened layer

70 pad portion

80 thin-film diode

81 upper electrode

82 lower electrode

100 element board

110 display region

111 to 114, 117 to 119 pixel formation portion

120 frame region

122,123,126,127,128,129 dummy pixel portion

130 source driver

140 gate driver

150 gate bus line

160 source bus line

170 storage capacitance line

180 display control circuit

200 counter board

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention and variants thereofwill be described with reference to the accompanying drawings.

<1. Overall Configuration and Operation>

First, the configuration and operation of a liquid crystal displaydevice according to an embodiment of the present invention will bedescribed with reference to FIG. 1.

FIG. 1 is a block diagram illustrating the configuration of the liquidcrystal display device according to the present embodiment, along withan equivalent circuit of a display portion thereof. As shown in FIG. 1,the liquid crystal display device includes an active matrix displayportion (display region) 110, a source driver 130 acting as a videosignal line drive circuit, a gate driver 140 acting as a scanning signalline drive circuit, and a display control circuit 180 for controllingthe source driver 130 and the gate driver 140. Since the overallstructure of the display device is similar to the above-describedstructure shown in FIG. 11, the same elements are denoted by the samecharacters, and descriptions thereof will be omitted. Note that pixelformation portions included in the display device are not provided withany reflective electrode as will be described later, and therefore thedisplay device effects only a transmissive display.

The display portion 110 includes: a plurality (m) of gate bus lines(also referred to as “gate lines”) GL1 to GLm, which correspond to theirrespective horizontal scanning lines for an image represented by imagedata contained in a video signal received by the display control circuit180 from an external signal source (not shown); a plurality (n) ofsource bus lines (also referred to as “data lines”) SL1 to SLn, whichcross each of the gate bus lines GL1 to GLm; and a plurality (m×n) ofpixel formation portions provided at their respective intersectionsbetween the gate bus lines GL1 to GLm and the source bus lines SL1 toSLn.

The pixel formation portions are disposed in the form of a matrix toconfigure pixel arrays, and each pixel formation portion forms apredetermined color: red (R), green (G), or blue (B). Each pixelformation portion is composed of: a TFT (thin film transistor) 10, whichis a switching element having a gate terminal connected to a gate busline GLj passing through a corresponding one of the intersections, and asource terminal connected to a source bus line SLk passing through theintersection; a pixel electrode connected to a drain terminal of the TFT10; a common electrode EC, which is a counter electrode commonlyprovided for the pixel formation portions; and a liquid crystal layercommonly provided for the pixel formation portions and disposed betweenthe pixel electrode and the common electrode EC. A pixel capacitance Cpis composed of a storage capacitance portion (auxiliary capacitance),which includes a capacitance formed by the pixel electrode and thecommon electrode EC, as well as a predetermined storage capacitanceline.

In the present embodiment, signals, such as an image data signal DArepresenting an image contained in a video signal that is to bedisplayed on a liquid crystal panel, a vertical synchronization signalVSY and a horizontal synchronization signal HSY, which aresynchronization signals for the video signal, and a clock signal CK, aresent from the external signal source (not shown) to the display controlcircuit 180.

The display control circuit 180 receives the vertical synchronizationsignal VSY, the horizontal synchronization signal HSY, and the clocksignal CK, and generates the following signals for causing the displayportion 110 to effect a display: a source driver start pulse signal SSP;a source driver clock signal SCK; a gate driver start pulse signal GSP;and a gate driver clock signal GCK. Note that these signals arewell-known, and therefore detailed descriptions thereof will be omitted.The display control circuit 180 also receives the image data signal DA,and supplies it to the source driver 130.

The source driver 130 receives the source driver start pulse signal SSP,the source driver clock signal SCK, and the image data signal DA fromthe display control circuit 180, and in accordance with these signals,the source driver 130 sequentially generates analog voltages, which areequivalent to pixel values on the horizontal scanning lines for theimage represented by the image data signal DA, as data signals S(1) toS(n), which are applied to their respective source bus lines SL1 to SLnin the display portion 110.

The gate driver 140 receives the gate driver start pulse signal GSP, andthe gate driver clock signal GCK from the display control circuit, andin accordance with these signals, the gate driver 140 sequentiallyselects each of the gate bus lines GL1 to GLm in the display portion 110for one horizontal scanning period during each frame period (verticalscanning period) for displaying the image represented by the image datasignal DA, and applies an active gate signal (a voltage to turn on theTFT 10) to the selected gate bus line.

As described above, the data signals S(1) to S(n) from the source driver130 are applied to the source bus lines SL1 to SLn, respectively, andthe gate signals G(1) to G(m) from the gate driver 140 are applied tothe gate bus lines GL1 to GLm, respectively, so that a voltage accordingto a value for a corresponding pixel for the image represented by theimage data signal DA is supplied to each pixel capacitance Cp in thedisplay portion 110 via the TFT 10, and held therein. As a result,voltages corresponding to potential differences between the pixelelectrodes and the common electrode EC are applied to the liquid crystallayer in accordance with the image data signal DA. The display portion110 controls optical transmittance of the liquid crystal layer inaccordance with the applied voltages to display the image represented bythe image data signal DA received from the external signal source. Theconfigurations of the display region 110 and the frame region 120 willbe described next with reference to FIGS. 2 and 3.

<2. Configuration of the Dummy Pixel Portion>

FIG. 2 is an enlarged top view as in FIG. 12, illustrating a detailedconfiguration of the element board 100 in the vicinity of the boundarybetween the display region 110 and the frame region 120. FIG. 2 showstwo pixel formation portions 112 a and 112 b, which are provided in thedisplay region 110 and have the same configuration, and a dummy pixelportion 122, which is provided in the frame region 120. Since the pixelformation portions 112 a and 112 b are configured in the same manner asthe pixel formation portions 111 a and 111 b shown in FIG. 12, exceptthat the reflective electrode 17 and the repair portion 18 are notincluded, the same elements are denoted by the same characters, anddescriptions thereof will be omitted. The gate bus lines 150, the sourcebus lines 160, and the storage capacitance line 170 are also configuredin the same manner as their counterparts, and therefore descriptionsthereof will be omitted.

The dummy pixel portion 122 shown in FIG. 2 has the functions of boththe dummy pixel portion 901 and the code notation portion 902 shown inFIG. 12, and includes a contact hole 12 identical to those of the pixelformation portions 112 a and 112 b, as well as a semiconductor layer 11,a contact hole 13, a through-hole 14, and a transparent electrode 16,which have the same functions as those in the pixel formation portions112 a and 112 b but are formed in different positions. Note that thelayered structure is the same as any one of the conventional layeredstructures as described earlier with reference to FIGS. 13A to 13D, andtherefore any description thereof will be omitted.

Here, in the dummy pixel portion 122, a gate electrode of a thin filmtransistor formed by the semiconductor layer 11 is divided into twoportions as shown in FIG. 2. By dividing the gate electrode into twoportions, rather than three portions as in the pixel formation portions112 a and 112 b, it becomes possible to form a transparent region(unused region) in the dummy pixel portion 122 to note a code 22.

Specifically, a source terminal of the thin film transistor at one endof the semiconductor layer 11 is connected to the source bus line 160via the contact hole 12, and a drain terminal of the thin filmtransistor at the other end of the semiconductor layer 11 extends out ofthe contact hole 13 toward the display surface of the element board 100(toward the counter board 200), and thereafter connected to thereflective electrode 17 via the through-hole 14. Therefore, by reducingthe number of gate electrodes to two, it becomes possible to shorten thedistances from the contact hole 12 to the contact hole 13 and to thethrough-hole 14. As a result, the positions in which to dispose thecontact hole 13 and the through-hole 14 can be changed in the directiontoward the bottom of FIG. 2 (i.e., the vicinity of the gate bus line 150connected to the dummy pixel portion 122), making it possible to ensurea wide transparent region within an area from the vicinity of the centerof the dummy pixel portion 122 to the contact hole 13 and thethrough-hole 14. In addition, with the above configuration, the thinfilm transistor of the dummy pixel portion 122 can have characteristicssimilar to those of the thin film transistors of the pixel formationportions 112 a and 112 b.

Note that even if the pixel formation portions 112 a and 112 b each havetwo gate electrodes, or four or more gate electrodes, by reducing thenumber of gate electrodes in the dummy pixel portion 122 to less thanthat number, it becomes possible to similarly ensure a wide transparentregion. In addition, if the length and position of the semiconductorlayer 11 can be changed by, for example, changing the position and sizeof the gate electrode in the dummy pixel portion 122, it becomespossible to similarly ensure a wide transparent region.

Furthermore, by providing the dummy pixel portion 122 with only oneelectrode that constitutes the storage capacitance line 170 from amongtwo electrodes equivalent to the two electrodes included in the storagecapacitance portion 15, it becomes possible to ensure a wide transparentregion. Specifically, of the two electrodes included in the storagecapacitance portion 15 in the pixel formation portion 112 a, 112 b, oneis provided on the side facing the storage capacitance line 170 (theside closer to the counter board 200), and the electrode equivalent tothat one electrode is omitted from the dummy pixel portion 122. Thewidth of the other electrode, i.e., the storage capacitance line 170, inthe dummy pixel portion 122 is reduced to the same width as a portion ofthe storage capacitance line 170 that extends outside the dummy pixelportion 122. Thus, it is possible to ensure a wide transparent regionwithin an area between the gate bus lines 150 respectively provided atthe top and bottom sides of the figure with respect to the storagecapacitance line 170 in the vicinity of the center of the dummy pixelportion 122.

In the wide transparent region thus ensured, the code 22 of the samesize as the conventional code 21 shown in FIG. 12 is noted. In FIG. 2,the number “111” is noted as the code 22. The code 22 is not made up of(the same material as) the reflective electrode as in the case shown inFIG. 13A, but (the same material as) any one of the following: thesource electrode, the gate electrode, and the semiconductor layer 11, asshown in FIGS. 13B to 13D, and therefore assignment of the codes 22 willnot increase the manufacture cost.

In addition, the dummy pixel portion 122 assigned with the code 22 asdescribed above has the function of the code notation portion 902 shownin FIG. 12, and includes the thin film transistor as in the conventionaldummy pixel portions, making it possible to prevent the pixel electrodesincluded in the pixel formation portions from being broken due to staticcharge. Furthermore, the dummy pixel portion 122 is positioned adjacentto one pixel formation portion, and has a conductor, which is formed soas to be spaced apart from pixel electrodes at the same distance as inother pixel formation portions, and therefore disposition of the dummypixel portion will not change parasitic capacitances (between conductorsor pixel electrodes) among the pixel formation portions. In addition,the dummy pixel portion 122 has a layered structure similar to that ofthe pixel formation portion 112 b adjacent thereto, and therefore itsvertical dimension (thickness) can be substantially the same as that ofthe display surface, so that the thickness of the liquid crystal layer(the cell gap) can be substantially uniform. Thus, the dummy pixelportion 122 has the same function as that of the conventional dummypixel portion 901 shown in FIG. 12.

As such, the dummy pixel portion 122 has the functions of both the dummypixel portion 901 and the code notation portion 902 shown in FIG. 12,and therefore the frame region 120 can be narrowed, so that the entiredisplay device can be rendered compact.

In addition, by using a portion of the frame region 120 that is widerthan in the conventional frame region (a region corresponding to theconventional code notation portion 902 shown in FIG. 12) as a region inwhich to bend (or lead around) wiring, such as the source bus line 160and the gate bus line 150, without narrowing the frame region 120(thereby rendering the entire display device particularly compact), itbecomes possible to suitably position the source driver 130 and the gatedriver 140 that are connected to the wiring.

FIG. 3 is a view illustrating an example where the source driver 130 andthe gate driver 140 are suitably positioned. As shown in FIG. 3, thesource driver 130 is disposed in a lower portion of the figure whenviewed from the display region 110, and displaced to the left side inthe figure, so that the source bus lines are provided so as to benddownward to the left. In addition, the gate driver 140 is disposed onthe right side in the figure, and displaced to the top side in thefigure, so that the gate bus lines are provided so as to bend upward tothe right. As such, the gate bus lines and the source bus lines can beprovided in such a manner as to be bent (or led around), so that thereis a wide extra region encircled by circle B shown in FIG. 3, which isnot used as a region in which to form the source driver 130 and the gatedriver 140. Accordingly, by forming any circuit or component forimplementing a predetermined additional function in the wide extraregion, it becomes possible to add a new function without increasing thesize of the display device. Note that even if only one of the sourcedriver 130 and the gate driver 140 is displaced as described above, asomewhat wide extra region as described above can be similarly provided,making it possible to add a new function without increasing the size ofthe display device.

<3. Effect>

As described above, in the present display device, the dummy pixelportions 122 having a function similar to that of the conventional dummypixel portions are formed in the frame region 120, and the codes 22 ofthe same size as the conventional codes 21 are noted in the dummy pixelportions 122, so that the frame region required for the dummy pixelportions and code notation can be reduced in size. As a result, thedegree of freedom in wiring layout of the frame region 120 duringdesigning can be increased, leading to a greater degree of freedom inlayout of various conductors and circuits, such as the source driver 130and the gate driver 140, within the frame region 120. Thus, it ispossible to add a new function without increasing the size of thedisplay device.

<4. Variants>

<4.1 First Variant>

Next, a first variant of the embodiment of the present invention will bedescribed with reference to FIG. 4. Unlike the display device accordingto the above embodiment, a display device according to the first variantdoes not effect a transmissive display, but only a reflective display.Accordingly, only the reflective electrode is used as the pixelelectrode of each pixel formation portion, and no transparent electrodeis used. However, configurations and operations of an equivalent circuitof the display portion and other elements are similar to those in theembodiment shown in FIG. 1. In addition, the pixel formation portions ofthe display device according to the first variant are configured in thesame manner as in the embodiment shown in FIG. 2, except that notransparent electrode is included as described above. Therefore, thesame elements are denoted by the same characters, and descriptionsthereof will be omitted.

FIG. 4 is an enlarged top view as in FIG. 2, illustrating a detailedconfiguration of the element board 100 in the vicinity of the boundarybetween the display region 110 and the frame region 120 in the firstvariant. FIG. 4 shows two pixel formation portions 113 a and 113 b,which are provided in the display region 110 and have the sameconfiguration, and a dummy pixel portion 123, which is provided in theframe region 120. Since the pixel formation portions 113 a and 113 b areconfigured in the same manner as the pixel formation portions 112 a and112 b shown in FIG. 2, except that the transparent electrode 16 isomitted, and instead, the entire pixel formation portion is covered onlyby a reflective electrode 37, descriptions thereof will be omitted. Inaddition, the gate bus lines 150, the source bus lines 160, and thestorage capacitance line 170 are also configured in the same manner astheir counterparts, and therefore descriptions thereof will be omitted.

The dummy pixel portion 123 shown in FIG. 4 includes a semiconductorlayer 11, a contact hole 13, and a through-hole 14, which are the sameas those in the dummy pixel portion 122 shown in FIG. 2, and the dummypixel portion 123 also includes the reflective electrode 37 made up of areflective electrode material, which differs in shape from, but is thesame as, that for the pixel formation portions 113 a and 113 b. Notethat the layered structure is the same as any one of the conventionallayered structures as described earlier with reference to FIGS. 13A to13D, and therefore any description thereof will be omitted.

Also, in the dummy pixel portion 123, a gate electrode of a thin filmtransistor formed by the semiconductor layer 11 is divided into twoportions, rather than into three portions as in the pixel formationportions 113 a and 113 b, so that as in the case of the dummy pixelportion 122, an unused region (corresponding to the transparent regionof the dummy pixel portion 122) in which to note a code 23 can be formedin the dummy pixel portion 123.

Furthermore, only an electrode equivalent to the storage capacitanceline 170 is provided in the dummy pixel portion 123, i.e., of the twoelectrodes included in the storage capacitance portion 15 in the pixelformation portion 113 a, 113 b, one is provided on the side facing thestorage capacitance line 170 (the side closer to the counter board 200),and an electrode equivalent to that one electrode is omitted from thedummy pixel portion 123. Thus, it is possible to ensure a wide unusedregion as in the dummy pixel portion 122.

The code 23 of the same size as the conventional code 21 shown in FIG.12 is noted in the wide unused region thus ensured. The code 23 isformed using the reflective electrode as in the case shown in FIG. 13A,but the code 23 itself is not formed by the reflective electrode, and isnoted by the reflective electrode 37 having some portions removed (cutout) to form the shape of the code 23 as shown in FIG. 4. As such, thecode 23 is formed using the reflective electrode 37 for the reflectivedisplay, and therefore assignment of the codes 23 will not increase themanufacture cost.

As with the conventional dummy pixel portions, the dummy pixel portion123 assigned with the code 23 makes it possible to prevent the pixelelectrodes included in the pixel formation portions from being brokendue to static charge, as well as to prevent parasitic capacitances inthe pixel formation portions from being changed, while making thethickness of the liquid crystal layer (the cell gap) substantiallyuniform. Thus, as with the dummy pixel portions 122, the dummy pixelportions 123 make it possible to narrow the frame region 120, therebymaking the entire display device compact.

In addition, by using a portion of the frame region 120 that is widerthan that in the conventional frame region as a region in which to bendwiring, such as the source bus lines 160 and the gate bus lines 150,without narrowing the frame region 120, it becomes possible to suitablyposition the source driver 130 and the gate driver 140 that areconnected to the wiring, and by forming any circuit or component forimplementing a predetermined additional function in an extra region thusgenerated, it becomes possible to add a new function without increasingthe size of the display device.

As such, by forming the dummy pixel portions 123 having the samefunction as the conventional dummy pixel portions in the frame region120 of the present display device, and noting the codes 23 of the samesize as the conventional codes 21 in the dummy pixel portions 123, itbecomes possible to reduce the size of the frame region required for thedummy pixel portions and code notation.

<4.2 Second Variant>

Next, a second variant of the embodiment of the present invention willbe described with reference to FIG. 5. As with the display deviceaccording to the above embodiment, a display device according to thesecond variant effects a transmissive display, and the configurationsand operations of an equivalent circuit of the display portion and otherelements are the same as those in the embodiment shown in FIG. 1. Inaddition, the configurations of pixel formation portions of the displaydevice are the same as in the embodiment shown in FIG. 2, except that arepair portion 18 is included as in the conventional display device.Therefore, the same elements are denoted by the same characters, anddescriptions thereof will be omitted.

FIG. 5 is an enlarged top view as in FIG. 2, illustrating a detailedconfiguration of the element board 100 in the vicinity of the boundarybetween the display region 110 and the frame region 120 in the secondvariant. FIG. 5 shows two pixel formation portions 114 a and 114 b,which are provided in the display region 110 and have the sameconfiguration, and a dummy pixel portion 122, which is provided in theframe region 120. The pixel formation portions 114 a and 114 b areconfigured in the same manner as the pixel formation portions 112 a and112 b shown in FIG. 2, except that the same repair portion 18 as theconventional repair portion 18 shown in FIG. 12 is included. Also, thegate bus lines 150, the source bus lines 160, and the storagecapacitance line 170 are configured in the same manner as theircounterparts, and therefore descriptions thereof will be omitted.

Here, the repair portion 18 is provided to repair any defect of thepixel formation portion that has occurred during manufacture, but therepair portion 18 is not limited to that composed of a pair ofelectrodes having a predetermined insulating layer sandwichedtherebetween. For example, a switching means, such as a backuptransistor, or a cut or connected end portion of a conductor, can beused so long as such an element is provided to change the wiring in thepixel formation portion.

Furthermore, since the dummy pixel portion 122 shown in FIG. 5 isconfigured in the same manner as the dummy pixel portion 122 shown inFIG. 2, the same elements are denoted by the same characters, anddescriptions thereof will be omitted. Here, the dummy pixel portion 122does not include any repair portion 18 as included in the pixelformation portions 114 a and 114 b, but this does not adversely affectthe function of the dummy pixel portion. The reason for this is that therepair portion 18 repairs any defect of the pixel formation portion thathas occurred during manufacture by changing the defective pixelformation portion that appears as a bright spot into a black spot,thereby making the display defect less noticeable, and therefore therepair portion 18 is not required by the dummy pixel portion that is notinvolved in effecting a display. In addition, parasitic capacitances inthe pixel formation portions do not change significantly even if therepair portion 18 is omitted.

As such, by forming the dummy pixel portions 122 having the samefunction as the conventional dummy pixel portions in the frame region120 of the present display device, and noting the codes 22 of the samesize as the conventional codes 21 in the dummy pixel portions 122, itbecomes possible to reduce the size of the frame region required for thedummy pixel portions and code notation.

<4.3 Third Variant>

Next, a third variant of the embodiment of the present invention will bedescribed with reference to FIG. 6. As with the conventional displaydevice shown in FIG. 12, a display device according to the third varianteffects a semi-transmissive display. Configurations and operations of anequivalent circuit of the display portion and other elements are thesame as those in the embodiment shown in FIG. 1. In addition, theconfiguration of pixel formation portions of the display device is thesame as that in the embodiment shown in FIG. 2, except that a repairportion 18 and a reflective electrode 17 are included as in theconventional pixel formation portions. Therefore, the same elements aredenoted by the same characters, and descriptions thereof will beomitted.

FIG. 6 is an enlarged top view as in FIG. 2, illustrating a detailedconfiguration of the element board 100 in the vicinity of the boundarybetween the display region 110 and the frame region 120 in the thirdvariant. FIG. 6 shows two pixel formation portions 111 a and 111 b,which are provided in the display region 110 and have the sameconfiguration, and a dummy pixel portion 122, which is provided in theframe region 120. The pixel formation portions 111 a and 111 b areconfigured in the same manner as the conventional pixel formationportions 111 a and 111 b shown in FIG. 12, and the gate bus lines 150,the source bus lines 160, and the storage capacitance line 170 areconfigured in the same manner as their counterparts, and thereforedescriptions thereof will be omitted.

Furthermore, since the dummy pixel portion 122 shown in FIG. 6 isconfigured in the same manner as the dummy pixel portion 122 shown inFIG. 2, the same elements are denoted by the same characters, anddescriptions thereof will be omitted. However, a code 22 of the dummypixel portion 122 may differ from that in the first variant, and may beformed by the reflective electrode as in the conventional dummy pixelportion as shown in FIG. 13A. Note that as described above, no adverseeffect is made to the function of the dummy pixel portion even if thedummy pixel portion 122 is not provided with the repair portion 18.

As such, by forming the dummy pixel portions 122 having the samefunction as the conventional dummy pixel portions in the frame region120 of the present display device, and noting the codes 22 of the samesize as the conventional codes 21 in the dummy pixel portions 122, itbecomes possible to reduce the size of the frame region required for thedummy pixel portions and code notation.

<4.4 Fourth Variant>

Next, a fourth variant of the embodiment of the present invention willbe described with reference to FIG. 7. As with the conventional displaydevice shown in FIG. 12, a display device according to the fourthvariant effects a semi-transmissive display. Configurations andoperations of an equivalent circuit of the display portion and otherelements are the same as those in the embodiment shown in FIG. 1, andpixel formation portions of the display device are configured in thesame manner as in the embodiment shown in FIG. 2, except that a repairportion 18 and a reflective electrode 47 are provided as in theconventional pixel formation portions. Therefore, the same elements aredenoted by the same characters, and descriptions thereof will beomitted.

FIG. 7 is an enlarged top view as in FIG. 2, illustrating a detailedconfiguration of the element board 100 in the vicinity of the boundarybetween the display region 110 and the frame region 120 in the fourthvariant. FIG. 7 shows two pixel formation portions 111 a and 111 b,which are provided in the display region 110 and have the sameconfiguration, and a dummy pixel portion 126, which is provided in theframe region 120. Since the pixel formation portions 111 a and 111 b areconfigured in the same manner as the conventional pixel formationportions 111 a and 111 b shown in FIG. 12, and the gate bus lines 150,the source bus lines 160, and the storage capacitance line 170 areconfigured in the same manner as their counterparts, descriptionsthereof will be omitted.

The dummy pixel portion 126 shown in FIG. 7 includes a semiconductorlayer 11, a contact hole 13, and a through-hole 14, which are the sameas those of the dummy pixel portion 122 shown in FIG. 2, and the dummypixel portion 126 also includes the reflective electrode 47 made up of areflective electrode material, which differs in shape from, but is thesame as, that for the pixel formation portions 111 a and 111 b. Notethat the layered structure is the same as any one of the conventionallayered structures as described earlier with reference to FIGS. 13A to13D, and therefore any description thereof will be omitted.

A code 26 of the same size as the conventional code 21 shown in FIG. 12is formed in an unused region of the dummy pixel portion 126. The code26 is made up of (the same material as) any of the following: the sourceelectrode, the gate electrode, and the semiconductor layer 11 as shownin FIGS. 13B to 13D, but unlike in these figures, the reflectiveelectrode 47 is formed so as to cover the entire surface of the dummypixel portion 126 when viewed from the counter board 200 side.Accordingly, the code 26 cannot be seen from the side facing the counterboard 200, due to blockage by the reflective electrode 47. However, asdescribed above, the code 26 is formed in the unused region, andtherefore can be seen from the side opposite to the side facing thecounter board 200. Accordingly, the code 26 shown in FIG. 7 is formed ina mirror-inverted shape when viewed from the side facing the counterboard 200, such that the code 26 is correctly noted when viewed from theside opposite to the side facing the counter board 200. In addition, asdescribed above, assignment of the codes 26 will not increase themanufacture cost. Note that as described above, no adverse effect ismade to the function of the dummy pixel portions even if no repairportion 18 is provided in the dummy pixel portions 126.

As such, by forming the dummy pixel portions 126 having the samefunction as the conventional dummy pixel portions in the frame region120 of the present display device and noting the codes 26 of the samesize as the conventional codes 21 in the dummy pixel portions 126, itbecomes possible to reduce the size of the frame region required for thedummy pixel portions and code notation.

<4.5 Fifth Variant>

Next, a fifth variant of the embodiment of the present invention will bedescribed with reference to FIG. 8. As with the display device accordingto the embodiment shown in FIG. 2, a display device according to thefifth variant effects a transmissive display. Configurations andoperations of an equivalent circuit of the display portion and otherelements are the same as in the embodiment shown in FIG. 1, and pixelformation portions of the display device are also configured in the samemanner as in the embodiment shown in FIG. 2. Therefore, the sameelements are denoted by the same characters, and descriptions thereofwill be omitted.

FIG. 8 is an enlarged top view illustrating a detailed configuration ofthe element board 100 in the vicinity of the boundary between thedisplay region 110 and the frame region 120, as well as in the vicinityof the source driver 130, in the fifth variant. FIG. 8 shows three pixelformation portions 117 a, 117 b, and 117 c, which are provided in thedisplay region 110 and have the same configuration, and three dummypixel portions 127 a, 127 b, and 127 c, which are provided in the frameregion 120 and have the same configuration. Since the pixel formationportions 117 a, 117 b, and 117 c are configured in the same manner asthe pixel formation portions 112 a and 112 b in the embodiment shown inFIG. 2, and the gate bus lines 150, the source bus lines 160, and thestorage capacitance line 170 are also configured in the same manner astheir counterparts, descriptions thereof will be omitted.

The dummy pixel portions 127 a, 127 b, and 127 c shown in FIG. 8 includea semiconductor layer 11, a contact hole 12, a contact hole 13, athrough-hole 14, and a transparent electrode 16, which are the same asthose of the pixel formation portions 117 a, 117 b, and 117 c. Note thatthe layered structure is the same as any one of the conventional layeredstructures as described earlier with reference to FIGS. 13A to 13D, andtherefore any description thereof will be omitted.

Here, in each of the dummy pixel portions 127 a, 127 b, and 127 c, agate electrode of a thin film transistor formed by the semiconductorlayer 11 is divided into three portions as in the pixel formationportions 117 a, 117 b, and 117 c as shown in FIG. 8. As a result, thedistances from the contact hole 12 to the contact hole 13 and to thethrough-hole 14 cannot be shortened, and therefore, unlike in theembodiment, the positions in which to dispose the contact hole 13 andthe through-hole 14 cannot be changed, so that no unused region can beformed in this regard.

However, unlike in the above embodiment, two electrodes included in astorage capacitance portion 15 provided in each of the pixel formationportions 117 a and 117 b, 117 c, one of the electrodes being equivalentto the storage capacitance line 170, are both omitted in the dummy pixelportions 127 a, 127 b, and 127 c shown in FIG. 8. As a result, in eachof the dummy pixel portions 127 a, 127 b, and 127 c, a wide transparentregion (unused region) can be ensured within an area between the gatebus line 150 and the through-hole 14, which are respectively provided atthe top and bottom sides in the figure with respect to the vicinity ofthe center of the dummy pixel portion. Note that the storage capacitanceportion 15 including the electrode that is equivalent to the storagecapacitance line 170 is used only for effecting displays, and thereforethe dummy pixel portions 127 a, 127 b, and 127 c (and all other dummypixel portions provided side by side in the same row) are dispensable,and may be omitted. Even if they are omitted, no problem will beincurred because substantially no change is made to parasiticcapacitances in the pixel formation portions adjacent to the dummy pixelportions in the same column.

The code 27 of substantially the same size as the conventional code 21shown in FIG. 12 is noted in the wide transparent region thus ensured.Unlike in the case shown in FIG. 13A, the code 27 is not composed of thereflective electrode, but it is made up of (the same material as) one ofthe following: the source electrode, the gate electrode, and thesemiconductor layer 11 as shown in FIGS. 13B to 13D, and thereforeassignment of the codes 27 will not increase the manufacture cost.

In addition, unlike in other variants and the above embodiment, thedummy pixel portions 127 a, 127 b, and 127 c in the present variantinclude a pad portion 70. The pad portion 70 is provided in the form ofa rectangle continuing from a portion of the source bus line 160 in anunused region in the vicinity of the contact hole 13 and thethrough-hole 14. A signal for a well-known test or evaluation analysisis externally inputted/outputted to/from the pad portion 70 via aneedle-like probe in contact therewith. The pad portion 70 is formed inthe unused region within the dummy pixel portions 127 a, 127 b, and 127c, and it is not necessary to form it in a dedicated area newly definedin the frame region 120 outside the dummy pixel portion as required inthe case of the conventional pad portions. Therefore, with thisconfiguration, it becomes possible to narrow the frame region 120,thereby rendering the entire display device compact.

Although the pad portion 70 is formed in continuation with a portion ofthe source bus line 160, it may be formed in continuation with a portionof the gate bus line 150, or in electrical connection with the contacthole 13. In addition, two or more of them may be formed.

As such, by forming the dummy pixel portions 127 a, 127 b, and 127 chaving the same function as the conventional dummy pixel portions in theframe region 120 of the present display device, and noting the code 27of the same size as the conventional code 21 in the dummy pixel portions127 a, 127 b, and 127 c, it becomes possible to reduce the size of theframe region required for the dummy pixel portions and code notation.Furthermore, by forming the pad portion 70 in the dummy pixel portions127 a, 127 b, and 127 c, it becomes possible to reduce the size of theframe region required for pad formation.

<4.6 Sixth Variant>

Next, a sixth variant of the embodiment of the present invention will bedescribed with reference to FIG. 9. As with the display device accordingto the embodiment shown in FIG. 2, a display device according to thesixth variant is an active-matrix display device, but there is adifference in that, instead of providing thin film transistors,thin-film diodes, which are known as switching elements similar to thethin film transistors, are provided on the element board 100. Thethin-film diodes each have a so-called MIM (metal-insulator-metal)structure consisting of upper and lower metal electrodes, and aninsulating layer sandwiched therebetween. Note that the details of thestructure are well-known, and therefore any description thereof will beomitted.

In addition, no gate bus lines are present on the element board 100, anda plurality of parallel scanning electrodes, which are equivalent to thegate bus lines, are formed on the counter board 200. The scanningelectrodes are provided so as to perpendicularly cross signal electrodesformed on the element board 100, which are equivalent to the source buslines. When a predetermined selection signal is applied to the scanningelectrodes, so that corresponding thin-film diodes are selected, avoltage corresponding to a voltage applied between each of the scanningelectrodes and a predetermined signal electrode is applied between thelower electrodes connected to their respective signal electrodes and theupper electrodes connected to their respective pixel electrodes. Theapplied voltage is written onto the thin-film diodes, so that electriccharge corresponding thereto is accumulated in the liquid crystal layer.The optical transmittance of the liquid crystal layer is controlled inaccordance with the applied voltage to display an image represented byan image data signal received from an external signal source.

FIG. 9 is an enlarged top view illustrating a detailed configuration ofthe element board 100 in the vicinity of the boundary between thedisplay region 110 and the frame region 120 in the sixth variant. FIG. 9shows two pixel formation portions 118 a and 118 b, which are providedin the display region 110 and have the same configuration, and a dummypixel portion 128, which is provided in the frame region 120.

The pixel formation portions 118 a and 118 b include a thin-film diode80, which includes an upper electrode 81 and a lower electrode 82, aswell as a transparent electrode 86 and a reflective electrode 87, whichare pixel electrodes. The present display device effects asemi-transmissive display by the transparent electrodes 86 and thereflective electrodes 87.

The dummy pixel portion 128 shown in FIG. 9 includes a thin-film diode80 including an upper electrode 81 and a lower electrode 82, which arethe same as those of the pixel formation portions 118 a and 118 b, aswell as a code 28 and a transparent electrode 86, but the reflectiveelectrode 87 is omitted. This configuration allows the code 28 to beviewed from the side facing the counter board 200, without being blockedby the reflective electrode 87. In addition, the code 28 is made up ofthe same material as the upper electrode 81, the lower electrode 82, orthe reflective electrode 87, simultaneously therewith. Thereby,assignment of the codes 28 will not increase the manufacture cost.

As such, by forming the dummy pixel portions 128 having the samefunction as the conventional dummy pixel portions in the frame region120 of the present display device, and noting the codes 28 of the samesize as the conventional codes 21 in the dummy pixel portions 128, itbecomes possible to reduce the size of the frame region required for thedummy pixel portions and code notation.

<4.7 Seventh Variant>

Next, a seventh variant of the embodiment of the present invention willbe described with reference to FIG. 10. Unlike the display deviceaccording to the embodiment shown in FIG. 2, a display device accordingto the seventh variant is a simple matrix display device. Since theoverall structure of the display device is the same as the structureshown in FIG. 11, the same elements are generally denoted by the samecharacters, and descriptions thereof will be omitted.

A plurality of parallel scanning electrodes are formed on the counterboard 200 of the display device, and a plurality of parallel signalelectrodes are formed on the element board 100 so as to perpendicularlycross each of the scanning electrodes. In accordance with voltagesapplied between the scanning electrodes and the signal electrodes, theoptical transmittance of the liquid crystal layer is controlled todisplay an image represented by an image data signal received from anexternal signal source.

FIG. 10 is an enlarged top view illustrating a detailed configuration ofthe element board 100 in the vicinity of the boundary between thedisplay region 110 and the frame region 120 in the seventh variant. FIG.10 shows two pixel formation portions 119 a and 119 b, which areprovided in the display region 110 and have the same configuration, anda dummy pixel portion 129, which is provided in the frame region 120.Note that the dummy pixel portion 129 is not provided with any switchingelement, and therefore differs from general dummy pixel portions, butthe dummy pixel portion 129 has a function in common with the generaldummy pixel portions, in that the cell gap can be cancelled as will bedescribed later.

The pixel formation portions 119 a and 119 b include a transparentelectrode 96 and a reflective electrode 97, which are pixel electrodes.The present display device effects a semi-transmissive display by thetransparent electrodes 96 and the reflective electrodes 97. The aboveconfiguration is the same as that in the sixth variant as describedabove.

However, unlike in the configuration according to the sixth variant, thedummy pixel portion 129 shown in FIG. 10 includes a transparentelectrode 96 and a reflective electrode 97. A code 29 is structured byappropriately positioning the reflective electrode 97 in the transparentelectrode 96. This configuration allows the code 29 to be viewed fromthe side facing the counter board 200, without being blocked by thereflective electrode 97, and even if the pixel formation portions areengaged in a reflective display or transmissive display, the code 29 isviewable. Furthermore, the code 29 is structured by the reflectiveelectrode 97, and therefore assignment of the codes 29 will not increasethe manufacture cost. Note that the fifth variant can be configured inthe same manner as the present variant, and the present variant can beconfigured without the reflective electrodes 97 as in the fifth variant.

However, it has been known that, in the case of the STN (super twistednematic) mode liquid crystal orientation, which is often employed bysimple matrix liquid crystal display devices, display unevenness isreadily caused due to nonuniform cell gaps. If the code 29 is formedonly by the transparent electrode 96, a cell gap is created due to adifference in electrode film thickness from the pixel formation portion119 b including the reflective electrode 97 disposed in its peripheralportion. Thus, as shown in FIG. 10, the code 29 is formed by disposingthe reflective electrode 97 and the transparent electrode 96,respectively, in a peripheral portion of the dummy pixel portion 129 andin the substantial center thereof, as well as by disposing an opaquematerial, such as the reflective electrode 97, in the electrode 96, itbecomes possible to cancel the cell gap due to the difference inelectrode film thickness, and thereby to prevent display unevenness.

In view of the above, when the STN-mode liquid crystal orientation isemployed in the fifth variant (or other examples), the code 28 (oranother code) is desirably structured with the reflective electrode 97being disposed in its peripheral portion as in the case of the code 29in the present variant.

<4.8 Other Variants>

The liquid crystal display devices according to the present embodimentand the variants thereof use liquid crystal for their display portions,but any display devices, which use electro-optical elements, such asorganic EL (electro luminescence) elements, or LEDs (light emittingdiodes), instead of using liquid crystal, may be applicable.

In the case of the liquid crystal display devices according to thepresent embodiment and the variants thereof, one or more electrodes thatare equivalent to two electrodes included in the storage capacitance areomitted in the dummy pixel portions, and the number of gate electrodesis reduced, so that the semiconductor layer 11 can be shortened, makingit possible to change the positions of the contact hole 13 and thethrough-hole 14 and thereby to form the unused region in which to notethe code (or dispose the pad portion). However, with or without use ofsuch a configuration, the unused region may be formed in the dummy pixelportions by narrowing the electrode width of the gate or source bus linein the dummy pixel portions. Also, in recent years, a memory circuit formemorizing potentials provided in the pixel formation portion, and asensor circuit for implementing the function of a scanner or touchsensor are formed in some cases. In such cases, the function of thedummy pixel portion is not compromised even if such circuits areeliminated from the dummy pixel portion, and therefore the unused regionmay be formed by eliminating the circuits.

In the case of the liquid crystal display devices according to thepresent embodiment and the variants thereof, the codes are formed on theelement board 100, but they may be formed on the counter board 200,using a thin film material (e.g., a color filter) for the counter board200. However, in order not to cause conductors and circuits that areformed on the element board 100 to partially or completely cover thecodes formed on the counter board 200, it is necessary to form theunused region according to the above-described configuration, e.g., oneor more electrodes that are equivalent to two electrodes included in thestorage capacitance are omitted in the dummy pixel portion, or thepositions of the contact hole 13 and the through-hole 14 are changed. Itis also necessary to form the codes within their respectivepredetermined regions on the counter board 200 that are positioned toface their corresponding unused regions formed on the element board 100.

INDUSTRIAL APPLICABILITY

The present invention is directed to display devices. More specifically,the present invention is applicable to display devices in which liquidcrystal elements or EL elements are disposed in the form of a matrix,and it is well-suited for liquid crystal display devices mounted in avariety of types of electronic equipment, particularly, such flat-paneldisplay device as to be mounted in mobile electronic equipment.

1. A display device comprising an element board and a counter board, theelement board including: a plurality of data signal lines fortransmitting a plurality of data signals; a plurality of scanning signallines crossing the data signal lines; a plurality of pixel formationportions disposed in a matrix form, the pixel formation portions beingprovided in a vicinity of their respective intersections between theplurality of data signal lines and the plurality of scanning signallines crossing the data signal lines; and a plurality of dummy pixelportions, each being disposed adjacent to an outermost one of the pixelformation portions, the counter board being provided so as to be opposedto the element board, such that electro-optical elements for effecting adisplay are sandwiched between the counter board and the element board,wherein the pixel formation portions each include a storage capacitanceportion having two electrodes for holding a potential in accordance witha signal supplied from a corresponding one of the data signal lines,wherein the dummy pixel portions include at least one componentequivalent to any one of a plurality of light blocking effect componentsfor forming a predetermined circuit included in the pixel formationportions, and an area of the component included in the dummy pixelportion, when viewed from a position substantially vertically away froma principal surface of the element board, is smaller than that of eachof the components included in the pixel formation portions, and thedummy pixel portions include an electrode equivalent to one of the twoelectrodes included in the storage capacitance portion, the electrodeincluded in the dummy pixel portions has a smaller area than that of theone electrode included in the pixel formation portion, wherein the dummypixel portions each include a code notation portion in which to note apredetermined code, and wherein the component included in the dummypixel portions is disposed so as not to prevent notation of the code. 2.The display device according to claim 1, wherein the pixel formationportions each include any one or more of the following components: arepair portion by which to change wiring in the circuit; a predeterminedmemory circuit; and a predetermined sensor circuit, and wherein thedummy pixel portions include none of the following: the repair portion,the memory circuit, and the sensor circuit, as included in the pixelformation portions.
 3. The display device according to claim 1, whereinone of the components included in the pixel formation portions is asemiconductor layer for forming a predetermined first thin filmtransistor, and wherein the component included in the dummy pixelportions is another semiconductor layer having a smaller area than thatof the semiconductor layer, and the dummy pixel portions each include asecond thin film transistor formed by the smaller semiconductor layer.4. The display device according to claim 3, wherein the first thin filmtransistor includes a plurality of gate electrodes, and wherein thesecond thin film transistor includes a lesser number of gate electrodesthan the number of gate electrodes in the first thin film transistor. 5.The display device according to claim 1, wherein the one electrodeincluded in the pixel formation portion is a storage capacitance line.6. The display device according to claim 1, wherein the componentsincluded in the pixel formation portions are a semiconductor layer, agate electrode, and a source electrode that form a predetermined thinfilm transistor, and wherein the notation of the code by the codenotation portion is achieved by forming one of the following into apredetermined shape: another semiconductor layer simultaneously formedwith the semiconductor layer; an electrode simultaneously formed withthe gate electrode; and an electrode simultaneously formed with thesource electrode.
 7. The display device according to claim 1, whereinone of the components included in the pixel formation portions is areflective electrode for effecting a reflective display, and wherein thenotation of the code by the code notation portion is achieved by formingan electrode of a predetermined shape, simultaneously with thereflective electrode.
 8. The display device according to claim 1,wherein the counter board includes code notation portions in which tonote a predetermined code within a region overlapping the dummy pixelportions when viewed from a position substantially vertically away froma principal surface of the counter board, and wherein the componentincluded in the dummy pixel portions is disposed so as not to preventnotation of the code.
 9. The display device according to claim 1,wherein the dummy pixel portions are coupled to either the data signallines or the scanning signal lines, or both, and include a pad portionby which to externally input/output a predetermined signal to/from thedevice.
 10. The display device according to claim 1, further comprisinga data signal line drive circuit for supplying the plurality of datasignals to their respective data signal lines, wherein the data signalline drive circuit is connected to conductors which are connected totheir respective data signal lines, and extend out of an end of theirrespective dummy pixel portions after being bent at a predeterminedangle in a direction in which the data signal lines extend.
 11. Thedisplay device according to claim 1, further comprising a scanningsignal line drive circuit for supplying a predetermined selection signalto the scanning signal lines, wherein the scanning signal line drivecircuit is connected to conductors, which are connected to theirrespective scanning signal lines, and extend out of an end of theirrespective dummy pixel portions after being bent at a predeterminedangle in a direction in which the scanning signal lines extend.
 12. Adisplay device comprising an element board and a counter board, theelement board including: a plurality of data signal lines fortransmitting a plurality of data signals; a plurality of scanning signallines crossing the data signal lines; a plurality of pixel formationportions disposed in a matrix form, and a plurality of dummy pixelportions, each being disposed adjacent to an outermost one of the pixelformation portions, the counter board being provided so as to be opposedto the element board, such that electro-optical elements for effecting adisplay are sandwiched between the counter board and the element board,wherein the pixel formation portions each include a storage capacitanceportion having two electrodes for holding a potential in accordance witha signal supplied from a corresponding one of the data signal lines,wherein the dummy pixel portions include at least one componentequivalent to any one of a plurality of light blocking effect componentsfor forming a predetermined circuit included in the pixel formationportions, and an area of the component included in the dummy pixelportion, when viewed from a position substantially vertically away froma principal surface of the element board, is smaller than that of eachof the components included in the pixel formation portions, and thedummy pixel portions include none of two electrodes equivalent to thetwo electrodes included in the storage capacitance portion, wherein thedummy pixel portions each include a code notation portion in which tonote a predetermined code, and wherein the component included in thedummy pixel portions is disposed so as not to prevent notation of thecode.
 13. A display device comprising an element board and a counterboard, the element board including: a plurality of data signal lines fortransmitting a plurality of data signals; a plurality of scanning signallines crossing the data signal lines; a plurality of pixel formationportions disposed in a matrix form; and a plurality of dummy pixelportions, each being disposed adjacent to an outermost one of the pixelformation portions, the counter board being provided so as to be opposedto the element board, such that electro-optical elements for effecting adisplay are sandwiched between the counter board and the element board,wherein components included in the pixel formation portions are firstsemiconductor layer, first gate electrode, first drain electrode, andfirst source electrode that form a predetermined first thin filmtransistor, wherein the dummy pixel portions include a plurality ofcomponents equivalent to any one of a plurality of light blocking effectcomponents for forming a predetermined circuit included in the pixelformation portions, and an area of the component included in the dummypixel portion, when viewed from a position substantially vertically awayfrom a principal surface of the element board, is smaller than that ofeach of the components included in the pixel formation portions, whereinthe components included in the dummy pixel portions are secondsemiconductor layer, second gate electrode, second drain electrode, andsecond source electrode that form a predetermined second thin filmtransistor, wherein the second gate electrode is smaller than the firstgate electrode, the second drain electrode is smaller than the firstdrain electrode, or the second source electrode is smaller than thefirst source electrode, wherein the dummy pixel portions each include acode notation portion in which to note a predetermined code, and whereinthe component included in the dummy pixel portions is disposed so as notto prevent notation of the code.
 14. The display device according toclaim 13, wherein the pixel formation portions each include any one ormore of the following components: a repair portion by which to changewiring in the circuit; a predetermined memory circuit; and apredetermined sensor circuit, and wherein the dummy pixel portionsinclude none of the following: the repair portion, the memory circuit,and the sensor circuit, as included in the pixel formation portions. 15.The display device according to claim 13, wherein the secondsemiconductor layer has a smaller area than that of the firstsemiconductor layer.
 16. The display device according to claim 15,wherein a number of the second gate electrodes is lesser than that ofthe first gate electrodes.
 17. The display device according to claim 13,wherein the notation of the code by the code notation portion isachieved by forming one of the following into a predetermined shape: thesecond semiconductor layer simultaneously formed with the firstsemiconductor layer; the second gate electrode simultaneously formedwith the first gate electrode; the second drain electrode simultaneouslyformed with the first drain electrode; and the second source electrodesimultaneously formed with the first source electrode.
 18. The displaydevice according to claim 13, wherein one of the components included inthe pixel formation portions is a reflective electrode for effecting areflective display, and wherein the notation of the code by the codenotation portion is achieved by forming an electrode of a predeterminedshape, simultaneously with the reflective electrode.
 19. The displaydevice according to claim 13, wherein the counter board includes codenotation portions in which to note a predetermined code within a regionoverlapping the dummy pixel portions when viewed from a positionsubstantially vertically away from a principal surface of the counterboard, and wherein the component included in the dummy pixel portions isdisposed so as not to prevent notation of the code.
 20. The displaydevice according to claim 13, wherein the dummy pixel portions arecoupled to either the data signal lines or the scanning signal lines, orboth, and include a pad portion by which to externally input/output apredetermined signal to/from the device.
 21. The display deviceaccording to claim 13, further comprising a data signal line drivecircuit for supplying the plurality of data signals to their respectivedata signal lines, wherein the data signal line drive circuit isconnected to conductors which are connected to their respective datasignal lines, and extend out of an end of their respective dummy pixelportions after being bent at a predetermined angle in a direction inwhich data signal lines extend.
 22. The display device according toclaim 13, further comprising a scanning signal line drive circuit forsupplying a predetermined selection signal to the scanning signal lines,wherein the scanning signal line drive circuit is connected toconductors, which are connected to their respective scanning signallines, and extend out of an end of their respective dummy pixel portionsafter being bent at a predetermined angle in a direction in which thescanning signal lines extend.
 23. A display device comprising an elementboard and a counter board, the element board including: a plurality ofdata signal lines for transmitting a plurality of data signals; aplurality of scanning signal lines crossing the data signal lines; aplurality of pixel formation portions disposed in a matrix form; and aplurality of dummy pixel portions, each being disposed adjacent to anoutermost one of the pixel formation portions, the counter board beingprovided so as to be opposed to the element board, such thatelectro-optical elements for effecting a display are sandwiched betweenthe counter board and the element board, wherein components included inthe pixel formation portions are first semiconductor layer, first gateelectrode, first drain electrode, and first source electrode that form apredetermined first thin film transistor, wherein the dummy pixelportions include at least one component equivalent to any one of aplurality of light blocking effect components for forming apredetermined circuit included in the pixel formation portions, and anarea of the component included in the dummy pixel portion, when viewedfrom a position substantially vertically away from a principle surfaceof the element board, is smaller than that of each of the componentsincluded in the pixel formation portions, wherein the component includedin the dummy pixel portions is any one or more of the followingcomponents that form a predetermined second thin film transistor: secondsemiconductor layer; second gate electrode; second drain electrode; andsecond source electrode, wherein the dummy pixel portions each include acode notation portion in which to note a predetermined code, and whereinthe component included in the dummy pixel portions is disposed so as notto prevent notation of the code.
 24. A display device comprising anelement board and a counter board, the element board including: aplurality of data signal lines for transmitting a plurality of datasignals; a plurality of scanning signal lines crossing the data signallines; a plurality of pixel formation portions disposed in a matrixform, and a plurality of dummy pixel portions, each being disposedadjacent to an outermost one of the pixel formation portions, thecounter board being provided so as to be opposed to the element board,such that electro-optical elements for effecting a display aresandwiched between the counter board and the element board, wherein thepixel formation portions each include a storage capacitance portionhaving two electrodes for holding a potential in accordance with asignal supplied from a corresponding one of the data signal lines, andwherein the dummy pixel portions include at least one componentequivalent to any one of a plurality of light blocking effect componentsfor forming a predetermined circuit included in the pixel formationportions, and an area of the component included in the dummy pixelportion, when viewed from a position substantially vertically away froma principal surface of the element board, is smaller than that of eachof the components included in the pixel formation portions, and thedummy pixel portions include one of two electrodes equivalent to the twoelectrodes included in the storage capacitance portion, wherein thedummy pixel portions each include a code notation portion in which tonote a predetermined code, and wherein the component included in thedummy pixel portions is disposed so as not to prevent notation of thecode.